The present invention relates to medical imaging, and more particularly, to automatic extraction of a silhouette of a 3D mesh represented anatomical structure segmented in a 3D image volume. Aortic valve disease affects a large number of people globally and is the most common type of valvular disease in developed countries. Implantation of a prosthetic aortic valve is often necessary to replace a severely damaged native valve. Although open-chest valve surgery is a well established procedure, minimally invasive transcatheter aortic valve implantation (TAVI) is an emerging technique, especially for high-risk patients, to minimize the surgical trauma. Interventional surgeries, such as TAVI, are typically performed under the guidance of real time fluoroscopic (x-ray) images. Many anatomical structures are not visible on these 2D x-ray images when no contrast agent is applied. Overlay with a 3D anatomical model extracted from other imaging modalities, such as computed tomography (CT), C-arm CT, or magnetic resonance imaging (MRI), can provide valuable visual guidance. Such a 3D anatomical model is often represented as a surface mesh. However, overlay with a solid mask of the anatomical structure generated from the surface mesh can be too intrusive and valuable information can be blocked by the mask.